The IP multimedia subsystem (IMS) is a new multimedia service defined in the 3rd Generation Partnership Project (3GPP) standards. The IMS meets the requirements for more novel and diverse multimedia services of end users nowadays. The IMS is a target network for a 3rd Generation (3G) mobile network to implement packet voice and packet data, and to provide uniform multimedia services and applications.
The IMS adopts an IP packet switched domain as a bearer channel for its control signaling and media transmission, and uses the Session Initiation Protocol (SIP) for call control signaling, so as to realize the separation of service management, session control and bearer access.
The Internet Protocol Television (IPTV) service is a new technology for providing various interactive services, including digital television for family users by using a broadband IP network, which combines various technologies such as Internet, multimedia, and communication. A user may use the IPTV service at home through a PC or a network set-top box plus a common television set, or may use the IPTV service through a mobile terminal. The IPTV uses a TCP/IP as the bearer protocol for unicast, broadcast or multicast of video services, so that three fields of television network, telephone network, and Internet are integrated effectively. Therefore, the IPTV is the most representative service of three-network convergence, which is attracting more and more attention from the industry.
The IMS based IPTV (IPTV based on the IMS) is to provide an IPTV service in an integral architecture of the IMS, so as to make full use of existing mechanisms for registration, authentication, routing, session control and establishment, service triggering, accounting, and end-to-end quality of service (QoS) assurance in an IMS network to provide streaming media services, as well as multimedia services that integrate streaming media and real-time session service for users.
The emergency alert system (EAS) releases an emergency event alert message to the public timely and accurately, for example, emergency messages about events threatening lives and properties including meteorological disasters, geologic hazards, toxic gas leakage, tsunami early warnings, earthquake early warnings, commotions, wars, and the like. For the IMS network and the IMS based IPTV system, a proper mechanism is required to release an emergency event alert to end users in time. The forms of the emergency event alert message may include text, audio, and video.
In the EAS service of conventional television, an emergency event alert message is transferred by changing content sources. That is, the emergency event alert message is transferred by switching content sources at a network side. For example, broadcast of current program content is suspended by a local television station, and the emergency event alert message is inserted. A user that watches the channel may then receive the emergency event alert message. However, if the channel that the user is watching has not broadcasted the emergency event alert message, the user cannot receive the emergency event alert in time. For example, a user is watching programs on a non-local television channel or even a foreign television channel while the local government department releases the emergency event alert message through the local television channel, so the user is unable to receive the message in time. Moreover, even if content sources of all channels transmitted to a local user are switched to the emergency event alert message at a local television relay station, still only users who are watching live television programs can receive the emergency event alert message. In the interactive IPTV, a user terminal is not only able to watch live television programs, but also is able to watch video on demand (VOD) programs, or operate an electronic program guide menu (EPG menu), play games, and the like, or even perform completely local operations such as watch locally saved programs, or perform video calling. In this way, these user terminals that are performing other operations instead of watching television programs at that time are unable to watch the emergency event alert message.
In the process for implementing the present invention, the inventors discovered at least the following problem in the prior art: the users who are not watching live television programs are unable to receive an emergency event alert in time.